A primary pollutant is defined as:

A primary pollutant is defined as a substance that is emitted directly into the atmosphere from a source in the same form as it exists. This includes gases like carbon monoxide, sulfur dioxide, and particulate matter that are released directly from processes such as combustion, industrial emissions, or natural events like volcanic eruptions. The significance of this definition highlights that primary pollutants do not undergo any chemical transformation before reaching the atmosphere; they are present in their original state.

The characteristic of primary pollutants is crucial for understanding air quality management and pollution control strategies, as these pollutants can have immediate health and environmental impacts. This is distinct from secondary pollutants, which are formed through atmospheric reactions involving primary pollutants, and therefore reflect a different aspect of air quality dynamics.

Overall, identifying primary pollutants accurately is essential for developing regulatory frameworks and implementing measures to control air pollution effectively.